1. Do it now activity
Last lesson we learnt about how images are stored on a computer. Can a computer decide what colours to use in an image? How does a computer know what colours to use?

2. Learning objectives
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could affect efficiency

3. Learning outcomes By the end of this lesson you will be able to ....
ALL
(C)
Explain how sound is represented on a computer using binary
MOST
(B)
Explain how a computer would use metadata to re-create an image
SOME
(A)
Explain what effect sample rate has on file size and sound quality

4. Find a picture to represent sound on the eardrum
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could affect efficiency
Learning
objectives
New Learning
What is sound?
Find a picture to represent sound on the eardrum
What is sound? Find a picture to represent sound on the eardrum.
Print off and stick in books
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

5. Amplitude and Frequency
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could affect efficiency
Learning
objectives
New Learning
Amplitude and Frequency
Work through several combinations
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

6. New Learning Amplitude is how loud the sound is Amplitude Frequency
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could affect efficiency
Learning
objectives
New Learning
Amplitude is how loud the sound is
Copy into books
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

7. New Learning Frequency is how often the sound is measured
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
New Learning
Frequency is how often the sound is measured
This is measured in Hertz (Hz for short)
Frequency is also called pitch
Copy into books
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

8. New Learning Amplitude Frequency Megahertz Sound Analogue Digitising
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
New Learning
A frequency of 1 Hz means one wave cycle per second. A frequency of 10 Hz means ten wave cycles per second, where the cycles are much shorter and closer together.
Audacity uses 44.1Khz. Even this is not good enough for the music industry. They use 44Khz
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

9. Talk Task On your whiteboards Is the sound quiet or loud?
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
Talk Task
On your whiteboards
Is the sound quiet or loud?
Is the sound low or high pitched?
Use audacity to record the following 2 sentences
In a quiet, squeaky voice (you are a mouse called “Amp”) ; say
“Amplitude is how loud the sound is, Squeak!”
In a loud deep voice, (you are an army sergeant called “Mega Hurts”) say;
“Frequency is measured in megahertz, Hoo-hah!”
Zoom in on the sound wave until you can see a clear line then play the sound for the mouse.
And Sergeant.
Students should answer the questions on their white boards
AMP – low amplitude, high frequency
Sergent – high amplitude, low frequency
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

10. Computers use sampling to re-create sounds
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
Independent Task 1 2
0.5 3 4
-0.5 5
-1.5 6 -1 7 8
Computers use sampling to re-create sounds
So how does the computer know what the sound sounds like?
Join the dots…you need to draw your own dots though! Here they are:
On the X axis, put a dot at the following co ordinates. Have a go at drawing the sound wave
You have just done what the computer does to reassemble an audio file.
To record a sound, the computer SAMPLES (aka, measures) the sound at regular points, (frequency). Then it converts the sample measurements into binary code.
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

11. Learning Development Amplitude Frequency Megahertz
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
Learning Development
The higher the sampling rate the smoother the curve.
Demonstrate this by opening an MP3 file in audacity, click on Effect > change tempo and decrease tempo without altering pitch – you can now hear the sampling
What does a computer use to break up a sound into smaller chunks? Answer on whiteboards - sampling
What are these samples converted into? Answer on whiteboards - Binary
How does the computer know that the binary should be treated as a sound file rather than an image file? Answer on whiteboards - Metadata
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

12. Independent Task Access on Weebly Term 3 - Lesson 4
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
Independent Task
Access on Weebly Term 3 - Lesson 4
Complete the independent task based on the level you are working towards
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

13. Plenary How is sampling a sound the same as digitising an image?
Recognise how sound is represented in a computer system
Investigate how computers use metadata to re-create sound
Investigate how an increased sample rate could effect efficiency
Learning
objectives
Plenary
How is sampling a sound the same as digitising an image?
Amplitude
Frequency
Megahertz
Sound Analogue Digitising
Sampling
Pitch
Binary

14. Learning outcomes By the end of this lesson you will be able to ....
ALL
(C)
Explain how sound is represented on a computer using binary
MOST
(B)
Explain how a computer would use metadata to re-create an image
SOME
(A)
Explain what effect sample rate has on file size and sound quality